SAN DIEGO — A novel sensor device may help inform contact lens wearers when their lens’ are unsafe to wear due to abnormally high levels of bacteria, according to findings presented at ASM’s 55th Interscience Conference of Antimicrobial Agents and Chemotherapy (ICAAC/ICC).

“We have devised a real-time sensing device, embedded within a contact lens case, which is capable of signaling the presence of abnormally high levels of live bacteria,” Nishal Govindji-Bhatt, post-doctoral research associate at the University of Manchester said in a press release. The researchers said this technology has potential for use as a research tool in clinical studies to monitor levels of bacterial growth associated with contact lens wear, and as a new approach to reducing eye infection and the use of antibiotics.

“The aim of the study was to develop a sensor (Microbiosensor) embedded in the base of a contact lens case that changes color when a high level of bacteria is present,” Govindji-Bhatt said in a press release. This would alert the contact lens wearer that they should not put the contact lens in their eyes.

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The chosen tetrazolium dye, commonly called MTT, caused a color change when the bacterial level reached just over a million counts in 1 mL of solution within eight hours. In tests, the Microbiosensor performance was not altered by the contact lens solution.

As part of the research, the sensor was fine-tuned with a range of chemical compounds called tetrazolium dyes, set in a semi-solid surface and embedded into contact lens cases. “We tested if a color change from yellow to dark blue would take place when harmful levels of bacteria were present, and ensured that the color change could be clearly seen by the user,” said Govindji-Bhatt.

Govindji-Bhatt and Curtis Dobson, along with a team of researchers at the University of Manchester conducted this work with funding from the Biotechnology and Biological Sciences Research Council and Medical Research Council. 


  1. Govindji-Bhatt N. Microbiosensor: A novel device for real-time monitoring of contact lens contamination. Abstract 2404. Presented at: ICAAC/ICC 2015; Sept. 17-21, 2015; San Diego.